Package Tour

One of the most profound benefits of object-oriented programming is reusability--programmers can save time, effort, and money by reusing objects created by other programmers. Typically, to make objects easier to find and use, and to avoid naming conflicts, programmers bundle groups of related objects into class libraries. In Java, class libraries are called packages.
Several packages of reusable classes are shipped as part of the Java development environment. Many of these packages also include interface and exception definitions.
The Java Language Package

This package provides classes that are core to the Java language. Even though the classes in this packages are generally useful, if you are writing stand-alone Java applications, you are likely to need the classes and interfaces in this package first, and if you are writing applets, you are likely to need the classes in the Applet and Abstract Window Toolkit packages first.

The Java I/O Package

The Java I/O Package provides a set of input and output streams used to read and write data to files or other input and output sources.

The Java Utility Package

This Java package contains a collection of utility classes. Among them are several generic data structures (Dictionary, Stack, Vector, Hashtable) a useful object for tokenizing a string and another for manipulating calendar dates. The java.util package also contains the Observer interface and Observable class which allow objects to notify one another when they change.

The Java Networking Package

Various networking classes comprise this package including classes that represent a URL and a URL connection, classes that implement a socket connection, and a class that represents an internet address.

The Applet Package

This package contains the Applet class -- the class that you must subclass if you're writing an applet. Included in this package is the AudioClip interaface which provides a very high level abstraction of audio.

The Abstract Window Toolkit Package

This toolkit provides GUI elements used to get input from and display information to the user such as windows, buttons, scrollbars, and text items. This packages, also known as the AWT, has two related packages: the java.awt.image and java.awt.peer packages.

AWT Image Package
The java.awt.image package contains classes and interfaces for working with images.
AWT Peer Package
[PENDING]

The Java Debugging Package

[PENDING]

See Also

Package Index for the API reference documentation

Table of Contents